Having trouble keeping chlorine level up

[Darrenmv]

My main question is why I can't maintain my chlorine level higher than 1.5 to 2.5 on average.

I run my T15 chlorine generator 14 hours/day at 80% (6am to 8pm every day) which I feel is longer than I should have to run it.
Salt between 3100 and 3400ppm. When I check my chlorine levels I get between 1.5 and 2.5. Most of the time my water stays clear.

I have had a black algae problem for many years that I just cannot seem to lick. I keep scrubbing and shocking. I even drained the pool, had it acid washed and refilled, and within 1 season the black algae was back.

I wonder if I could keep the chlorine levels higher on average if that would help.
It seems I am either not generating enough chlorine for my 35k gallon pool or I am doing something else wrong that is not allowing the chlorine level to get higher and stay there.

My pool gets used maybe 10 times per year so almost no bather load at all now that my kids are grown and gone.
I have the pool mostly because I like sitting out by it or seeing it outside my glass walls. Not much swimming.

However, my pool does get 100% full sun all day here in south Louisiana. The water gets quite hot in peak summer. Over 90F.
Also, we get tons of rain so I have to add salt, CYA to combat the washout from the rain.
I have a cartridge filter system so I don't lose any chemicals from backwashing.

Any suggestions would be greatly appreciated.

 

[markayash]

Have you tried adding liquid chlorine just to see if the level goes up. If it still won’t hold your still battling algae

Might be easier to just do a over night chlorine loss test and see if it's algae

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

 

[Darrenmv]

Sunday night I added 8 bottles of chlorine bleach because it started getting bright green algae on the walls (chlorine level tested to 2.5). I also switched my chlorinator to 80% 24/7 at the same time. It's been running 24/7 since Sunday. The water cleared up right away. I have not tested the chlorine level since Sunday night. I can test it when I get home today.

 

[pjt]

How are you testing?

 

[Darrenmv]

I use the Taylor K-2006 test kit

 

[pjt]

I use the Taylor K-2006 test kit

Would you please add that to your signature?

 

[Darrenmv]

I just tested the chlorine level. It is 2.5ppm. The pump and chlorinator have been running 24/7 at 80% since Sunday. Apparently the 8 gallons of bleach I added Sunday after dark have been used up.

 

[markayash]

I just tested the chlorine level. It is 2.5ppm. The pump and chlorinator have been running 24/7 at 80% since Sunday. Apparently the 8 gallons of bleach I added Sunday after dark have been used up.

Sounds like your Algae issue is still around

 

[gingrbredman]

Darren, looks like you have been around here since 2014, so you may have read some of this already, but here are some thoughts.

I run my T15 chlorine generator 14 hours/day at 80% (6am to 8pm every day) which I feel is longer than I should have to run it.

I would ask, why do you think it is longer than you should run the pump? Not sure which pump you have, but if it is a VSP, you could run it low and slow 24/7, still get the skimming functions you need, and not spend a lot on electricity. You could also set your salt cell percentage to generate the amount of chlorine you need to keep with your needs.

What is your CYA level? I see you test with the Taylor kit, so the results may be helpful for others as well to see what the whole pool chemistry looks like.

Based on the Pool Math app, if you are running your pump and cell at those rates, you are adding only 2.4 ppm of chlorine in that time. The T15 cell, running 24/7, at 100% output in your pool will give you 4.1 ppm of chlorine per day, which is probably not enough based on your location and sun.

However, my pool does get 100% full sun all day here in south Louisiana. The water gets quite hot in peak summer. Over 90F.

In the peak of summer, you could lose 2-5 ppm per day of chlorine to the sun alone. With the settings you are running, you are only adding 2.4 ppm per day. Again, the CYA level will determine the right chlorine level you need, but let's assume it should be at least 60 based on your location, your minimum chlorine should be 3 and a target of 4. Of course we never want to skirt the low end of the ranges, so you really should be looking to keep chlorine higher than that.

My main question is why I can't maintain my chlorine level higher than 1.5 to 2.5 on average

Without seeing all the test results, I would just be guessing, but it looks like you are not producing enough chlorine from your cell to keep up with the demands. Burning off 2-5ppm per day, and adding only 2.4 per day, is going to result in low chlorine levels and......

I have had a black algae problem for many years that I just cannot seem to lick. I keep scrubbing and shocking. I even drained the pool, had it acid washed and refilled, and within 1 season the black algae was back.

The first thing to do is....

Might be easier to just do a over night chlorine loss test and see if it's algae

Go ahead and see what the OCLT tells you. Make sure you also perform the entire body of tests because they will be important to what you do next. Algae is going to require you to get on the SLAM to get rid of it.

In the future, once you clear all this up, you probably need to adjust your pump run and cell output in order to keep up with the chlorine demand. Running your T-15 cell, with a 34k gallon pool is only going to give you 4ppm of chlorine per day, which at times in the high sun may not be enough to keep up. Not sure how old the cell is, but when its time to change it, look for one with a higher output and you can use liquid chlorine for now to keep with with the shortfall.

 

[Darrenmv]

Darren, looks like you have been around here since 2014, so you may have read some of this already, but here are some thoughts.


I would ask, why do you think it is longer than you should run the pump? Not sure which pump you have, but if it is a VSP, you could run it low and slow 24/7, still get the skimming functions you need, and not spend a lot on electricity. You could also set your salt cell percentage to generate the amount of chlorine you need to keep with your needs.

What is your CYA level? I see you test with the Taylor kit, so the results may be helpful for others as well to see what the whole pool chemistry looks like.

Based on the Pool Math app, if you are running your pump and cell at those rates, you are adding only 2.4 ppm of chlorine in that time. The T15 cell, running 24/7, at 100% output in your pool will give you 4.1 ppm of chlorine per day, which is probably not enough based on your location and sun.


In the peak of summer, you could lose 2-5 ppm per day of chlorine to the sun alone. With the settings you are running, you are only adding 2.4 ppm per day. Again, the CYA level will determine the right chlorine level you need, but let's assume it should be at least 60 based on your location, your minimum chlorine should be 3 and a target of 4. Of course we never want to skirt the low end of the ranges, so you really should be looking to keep chlorine higher than that.


Without seeing all the test results, I would just be guessing, but it looks like you are not producing enough chlorine from your cell to keep up with the demands. Burning off 2-5ppm per day, and adding only 2.4 per day, is going to result in low chlorine levels and......


The first thing to do is....


Go ahead and see what the OCLT tells you. Make sure you also perform the entire body of tests because they will be important to what you do next. Algae is going to require you to get on the SLAM to get rid of it.

In the future, once you clear all this up, you probably need to adjust your pump run and cell output in order to keep up with the chlorine demand. Running your T-15 cell, with a 34k gallon pool is only going to give you 4ppm of chlorine per day, which at times in the high sun may not be enough to keep up. Not sure how old the cell is, but when its time to change it, look for one with a higher output and you can use liquid chlorine for now to keep with with the shortfall.

Thanks for all the helpful info. I will try to run all tests when I get home tonight and also see about running the OCLT and post my results here. Also, I have been considering upgrading my chlorine generator to a Circupool RJ-60 PLUS. Any thoughts on Circupool equipment?

 

[markayash]

Thanks for all the helpful info. I will try to run all tests when I get home tonight and also see about running the OCLT and post my results here. Also, I have been considering upgrading my chlorine generator to a Circupool RJ-60 PLUS. Any thoughts on Circupool equipment?

Most folks have had good luck with Circupool, I have the Egde40 and a 22000 gallon pool and love it.
Discount salt pools is the best seller and seems top be tied with them somehow.

I think your current issue is algae and you mentioned Black Algae. Its stubborn but they have a good article about controlling it.

Black Algae

This guide provides a step by step procedure for eliminating black algae in your concrete or gunite pool. Read full post here.

www.troublefreepool.com

 

[reggiehammond]

Important to point out that you need to perform the OCLT with the SWCG off, before we can start blaming it.
Once your water is clear after a good SLAM, we can perform a OCGT (gain test) over night to see if the SWCG is producing FC.

But the main issue now should be liquid chlorine and a good SLAM.

 

[gingrbredman]

Important to point out that you need to perform the OCLT with the SWCG off, before we can start blaming it

Great point Reggie, you can not perform a OCLT with the SWCG running. Make sure it is off. You do not want the SWCG adding chlorine to the water when you are trying to see how much gets burned up overnight.

No one is looking to blame the SWCG itself, but running it as low as it has been running, it was likely an opportunity for the algae to take hold.

But the main issue now should be liquid chlorine and a good SLAM.

Right on! This is priority #1. After you get the TFP water you are looking for, can consider a plan to use the cell you have, supplementing with LC along the way, or upgrading the undersized cell to something more suited for a 34k gallon pool.

I will try to run all tests when I get home tonight and also see about running the OCLT and post my results here.

Can't wait to see these results, you have a lot of support here to get that perfect water you have been searching for.